There is no guide to the size of the holes to be drilled. Unforgivable. It took me 1 1/2 hours; would be done in half the time with guidance. One of the wheels immediately fell out and stepped over the sill of a small rug. If I hadn't had 45 years of property management I would never have been able to successfully install and level them. If I ever receive something similar in the future it will be returned as defective. Who wants their time wasted. For reference, I first drilled a 1 3/8" pilot hole with a 3/16" drill bit; then the final cut with a 3/8" bit. It was necessary to check the actual depth with a 3/16" chisel as the upside down table can pick up sawdust where the arm/rod of the Handlebar must fit snugly through adapter to stay in. safe. Perhaps for safety reasons a 1 1/2" deep hole might work better. However, this should be clearly presented in a 2-3 line guide or a simple picture if the manufacturer cannot write in English!